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DAVIDSON LABORATORY

REPORT SIT DL-75-18^0

October 1975

PRELIMINARY HYDRODYNAMIC MODEL TESTS

OF

SEVERAL LVA PLANING HULL CONCEPTS

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u £ &

by

Daniel Savitsky

Edward Numata

Michael Chioaao

SlLVt NS INSTITUTE in 1KHNOLOGY

CASH l POINT STATION HOBOKhN. NtW JERSEY 07030

\ Prepared for

Code 03221 cfNaval Sea Systems Command under

Off ice of Naval Research Contract N0001'4-75-C-07i«6

Project No. NR 062-510 (Davidson Laboratory Project *«28l/17l)

APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED

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PRELIMINARY HYDRODYNAMIC MODEL TESTS OF SEVERAL LVA PLANING HULL CONCEPTS

5. TYPE OF REPORT 4 PERIOD COVERED

FINAL REPORT

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Contract N000I4-75-0-07^6 Proj. NRQ62-510/1-09-75(438

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Davidson Laboratc~y Stevens Institute of Technology Hoboken, N.J. 07030

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II SUPPLEMENTARY NOTES

If. KEY WORDS (Conllnu« on r«v«n« «Id« II nocooory and »dtnUly by block -lumbar)

Planing; Seakeeping; Amphibious Craft

10. ABSTRACT fConllnu« on r«var«« «Id« If n«c«««ary awd Idtnliiy by block numb««;

\,y Exploratory hydrodynamic model tests were conducted to investigate the re- sistance and seakeeping character of two possible LVA planing hull forms. Additional studies were made to evaluate the effects on hydrodynamic per- formance of adjustable transom flaps and fixed chine flaps. For a 55,000 lb. gross weight, the planing inception speed was between 10 and 15 knots. The impact accelerations and motions in a head sea state 2 are comparable with

(Cont'd) -■ -'' - '

DD i JAN"TJ 1473 ^EDITION OF I NOV SS IS OBSOLETE S/N 0102-01«-6601 I

SECURITY CLASSIFICATION OF THIS PAGE fWion Data Cnfaradj

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with those observed for well-designed planing hulls and appear to be within the requirements for maintaining proficiency as defined by MIL- STD 1U72-A. The added resistance in a head sea is larger than for conventional planing hulls. Bow form improvements are recommended to reduce the resistance and accelerations in a seaway. Computed and measured values of EHP and trim for zero flap deflection are in good agreement.

.r

SECURITY CLASSiriCATlOM OF THIS PAGEfMiM» D»f Enffd)

STEVENS INSTITUTE OF TECHNOLOGY DAVIDSON LABORATORY CASTLE POINT STATION HOBOKEN. NEW JERSEY

REPORT SIT-DL-75-J8^0

Ocl«jg|D75

PRELIMINARY HYDRODYNAMIC MODEL TESTS

OF

SEVERAL LVA PLANING HULL CONCEPTS

by

Daniel Savitsky

Edward Numata

Michael Chiocco

Prepared for

Code 03221 of Naval Sea Systems Command under

Office of Naval Research Contract N00001W5-C-07H

Project Ho. NR-062-510N,I |OI

(Davidson Laboratory Project &281/170

Y

R-I8l»0

TABLE OF CONTENTS

Page

ABSTRACT ii

INTRODUCTION 1

MODELS AND APPARATUS 2

TEST PROCEDURE 4

TEST RESULTS 6

Smooth Water Results 6

Rough Water Results 6

DISCUSSION OF TEST RESULTS 8

Smooth Water Performance 8

0 Transom Flap and No Chine Flap 8 Effect of Transom Flaps 8 Effect of Chine Flaps 9 Effect of Increased Displacement 9 Effect of LCG Position 10 Maximum Lift-Drag Ratio for P-l Model 10 Effect of Zero Deadrise 10 Effect of Large Transom Flap 11 Porpoising Tendency 11 Summary of Smooth Water EHP 11

Performance in Head Sea State 2 11

Significant Pitch Motions 12 Significant Heave Motions 12 Significant Bow Accelerations 12 Significant Center-of'-Gravity Accelerations IS Significant Stern Accelerations 13 Comparison of LVA Accelerations with Those

for Other Planing Craft 13 Estimate of Habt lability in a Seaway 13 Mean Effective Horsepower (EHP) in Waves 15

Comparison of Measured and Predicted Smooth Water EHP for 0 Transom Flap. 26'

CONCLUSIONS 18

Smooth Water 18

Rough Water 18

ACKNOWLEDGEMENT 20

REFERENCES 21

TABLES 1 - 9

FIGURES 1 - 22

APPENDICES A-D

R-lMO -i i-

ABSTRACT

Exploratory hydrodynamic model tests were conducted to investigate

the resistance and seakeeping character of two possible LVA planing hull

forms. Additional studies were made to evaluate the effects on hydro-

dynamic performance of edjustable transom flaps and fixed chine flaps.

For a 55,000 lb. gross weight, the planing inception speed was between

10 and 15 knots. The impact accelerations and motions in a head sea

state 2 are comparable with those observed for well-designed planing

hulls and appear to be within the requirements for maintaining proficiency

as defined by MIL-STD 1^72-A. The added rasistance in a head sea is larger

than for conventional planing hulls. Bow form improvements are recommended

to reduce the resistance and accelerations in a seaway. Computed and

measured values of EHP and trim for zero flop deflection are in good agree-

ment.

KEYWORDS

Planing

Seakeeping

Amphibious Craft

R-lMO

INTRODUCTION

One of the possible versions of the LVA is a low deadrise, hard

chine, planing hull. Because of the dimensional constraints and large

loadings associated with its mission, the bottom loading of the LVA is

considerably larger than conventional planing craft. As a consequence,

the running trim and drag-lift ratio at hump speed have been estimated

to be larger than that of conventional planing hulls. In order to provide

some hydrodynamic design guidance for an LVA planing concept, an explora-

tory model test program was undertaken to define the smooth water resis-

tance, and motions, impact loads and resistance in a head sea state 2

for a range of speeds and loadings.

Two basic planing hull configurations were model-tested. One was

a so-called inverted vee-bottom which wss developed by the LVA office at

NSRDC and the other was a flat-bottom planing hull. The overall dimen-

sions and loadings were the same for both models. Adjustable aluminum

transom flaps and fixed chine flaps were added to the basic hull models

in order to evaluate their hydrodynamic effectiveness in smooth and rough

water.

The model test results were analyzed to identify the _§HP require-

ments; estimate personnel tolerance of g loads in a seaway; effectiveness

of transom and chine flaps; adequacy of predictive techniques; and hull

form changes to improve hydrodynamic performance. Basically, the tests

were expected to provide fundamental hydrodynamic data related to highly-

loaded planing hulls in smooth and rough water and to identify possible

options in the LVA design process.

This study is in support of a development program initiated by Code

03221 of the Naval Sea Systems Command. The work was carried out under

Office of Naval Research Contract N0001'4-75-c-07'«6, Project NR 062-510.

Technical monitoring was provided by the LVA office at NSRDC.

R-18A0 -2-

MODELS AND APPARATUS

The test models were 1/12-scale and were constructed of fiberglass-

covered polyurethdne. The inverted vee-bottom hull was constructed in ac-

cordance with prototype drawings supplied by NSRDC (Figure 1 ) and is re-

ferred to as the P-l model. It is seen that the inverted vee cross-section

exists primarily in the bow area and reduces to zero deadrise at the stern.

The flat bottom hull model was developed by the Davidson Laboratory and is

shown in Figure 2.

An adjustable, partial span, transom flap having a full-scale chord

of 3 ft. and a span of 6.5 ft. was hinged to each hull bottom at the aft

"break" point in the buttock lines (Figure 3)- This flap was capable of

deflecting downward to a maximum of 15 in 2.5 degree increments. A zero

degree flap angle refers to the flap oriented as a horizontal extension of

the planing bottom. The flap is hinged at the aft break point in the but-

tock lines since this is the point of flow separation when planing without

transom flaps. Although negative flap angle settings were available, this

variation was not model-tested in the first exploratory study. Further,

the flap chord was fixed at 3 ft. although large flap sizes could be easily

accommodated. One brief series of smooth water tests were made with a

full span flap installed on the flat bottom hull. (Figure 3)

Both model forms were tested with and without 3 ft. (prototype size)

wide chine flaps attached to each side of the model. These chine flaps

started at the break point of the aft buttock lines and extended forward

nearly 2/3 of the hull length. (Figure 3)

Each hull bottom was inscribed with black lines, one tenth of a

foot apart, to estimate wetted lengths from underwater photographs. Side

wetted lengths were obtained from similar side markings. The model tow

pivots and heave reference were located at the model CG for all configura-

tions. The weights of the heave mast, pivot box, drag balance, and three

acceleromet :rs were included in the ballasting for each condition. The

stern and bow accelerometer positions were on the centerline four (k) and

twenty-four (2k) feet from the transom, respectively, for all cases. The

bow accelerometer is located in the anticipated pilot station and the stern

accelerometer is in the troop compartment of an LVA.

Full-scale characteristics of the tested configurations were obtained

from the LVA office of NSRDC and are as follows:

R-18^0 -3-

50,0001}

LVA P-l

55,0001} 60, 0001}

LVA Flat** Bottom Hull

55,00011

LOA, ft. 28 28 28 28

Beam, ft. 11 11 11 11

Hull Depth, fc. 7 7 7 7

LCG Fwd Transom ft. 12.5 12.5 12.5 12.5

- 13.5 - -

VCG Above Baseline, ft. 3.5 3.5 3-5 3-5

Mean Draft, ft. 3.07 3.35 3-58 3.35

Pitch Gyradius, ft. 7 7 7 7

Static Floating Trim, deg.

LCG 12.5 -0.1 0 0.1 0.6

LCG 13.5 - -3-2 - -

Plus trim means bow up A*

A 0.5 ft. by 11 ft. spray deflector normal to the bow at a povnt 4' above the baseline was fitted to the craft prior to irregular seas testing.

R-1840

TEST PROCEDURE

The models were towed over a simulated full-scale speed range of

10 to ^0 knots in calm water to obtain trim, heave, wetted length and re-

sistance data for use in determination of smooth water EHP and as a basis

for evaluating added EHP when running "n a seaway. Model resistance was

expanded to full size in salt water at 59 F based on the ATTC model-ship

correlation coefficients with zero roughness allowance. Proper allowance

was made to simulate thrust unloading when the model was trimmed. The

propeller axis was taken to be parallel to and 1.25 ft. below trie base line.

The model was towed at constant speeds over the speed range into

irregular head sea state 2 with significant full-scale wave height of 2.2 ft.

In Reference 1, it is shown that rough water testing of planing hulls pro-

vides similar results at either constant speed or constant thrust. Resis-

tance, pitch and heave about the CG were measured with linear differential

transformers, and accelerations normal to the baseline at stern, CG, and

bow were measured with linear accelerometers with a frequency response

flat to 100 hertz. A standard Davidson Laboratory resistance-type wave

wire was used to measure waves at a fixed point in the tank. Data were

transmitted to shore through overhead cables and were recorded in analog

form on magnetic tape and simultaneously as time histories on a direct writ-

ing oscillograph. Data were recorded for a distance of 50 feet in calm

water and 1*40 feet in irregular seas.

During the tests, the transducer outputs were processed on-line by

a digital computer to furnish statistical averages of the craft responses.

This output included mean drag, average running trim and heave; also aver-

ages of 1/3-highest of upward acceleration at the stern, CG, and bow and

of pitch and heave amplitudes. Average trim is the inclination of the

craft's baseline to the horizontal; average heave is referred to a static

floating zero; acceleration is a change from a floating zero. Because of

the exploratory nature of this initial test program, approximately 25-30

waves were encountered during a test run. An ideal statistical sample

usually contains approximately 100 wave encounters. Nevertheless, it is

believed that the present test results are adequate for the purposes of

this exploratory study.

R-lMO -5-

The reproducible irregular seas generated in the Tank 3 facility

of the Davidson Laboratory approximate the Pierson-Moskowitz spectrum

shape. The spectrum used in this investigation is presented in Figure

19 and compares with the Pierson-Moskowitz spectrum. Color 16mm silent

motion pictures were taken for part of each run tested. When viewed at

a projection speed of 16 frames per second, a full-scale time for each

prototype is simulated. A movie sequence is presented in Appendix A.

Video tape records were obtained for all runs. A test matrix for each

configuration is presented in Appendices B, C and D.

A matrix of smooth water test conditions is given in Appendices

B and C The rough water test matrix is given in Appendix D.

R-IMO -6-

TEST RESULTS

All model test results have been extrapolated to full-scale values

and are so presented in this report.

Smooth Water Results

Results for all configurations and test conditions are presented in

Tables 1 through 7 and in chart form in Figures k through 11. It will be

noted that the tabulated values include test speed, transom flap deflec-

tion, drag, EHP, equilibrium trim of the base line, CG, heave relative

to the static floating position, maximum wetted length, and total wetted

areas including bottom and side wetting. EHP is defined as bare hull re-

sistance multiplied by speed and divided by 550. An estimate of the shaft

horsepower (SHP) is dependent upon the appendages, propeller characteristics

and machinery which have not been considered in this study. Tables 1, 2

and 3 and Figures *», 5 and 6 represent results for the inverted vee-bottom

(model P-l) without chine flaps for gross weights of 50,000 lbs., 55,000 lbs.

and 60,000 lbs. respectively—alI for an LCG of 12.5 ft. forward of the

transom. Table k and Figure 7 present similar results for the P-l for a

gross weight of 55,000 lbs. and the LCG moved to a distance of 13-5 ft.

forward of the transom. Table 5 and Figure 8 present the data for the P-l

with added fixed chine flaps at a cjiuss weight of 55,000 lbs. and an LCG

of 12.5 ft. forward of the transom. Data for the flat bottom hull with

and without chine flaps for a loading of 55,000 lbs. and an LCG of 12.5 ft.

forward of the transom are given in Tables 6 and 7 and Figures 9 and 10.

A summary plot of smooth water EHP is given in Figure 11.

Rough Water Results

j Table 8 presents rough water test results for the P-l model with

and without chine flaps and for the flat bottom model with chine flaps.

j These were the cnly configurations tested in a seaway. The data are re-

1 tabulated in Table 9 for ease in comparing the behavior of the three hull

forms. In addition, Table 9 also contains listings of the smooth water

trim angles for identical test conditions. All data are also plotted in

Figures 12 through 18.

In order to put the LVA impact data into proper perspective, the

significant center-of-gravity accelerations are compared in Figure 20 with

some ad hoc planing hulls previously tested at Davidson Laboratory. These

^»■MSBB

R-1840 -7-

data are also presented as 1/3 octave band rms g's versus encounter fre-

quency and compared with MIL-STD 1^72A habitability criteria in Figure

21.

Color 16mm silent motion pictures of selected test runs have been

submitted to NSRDC.

r

^^^^^^^^j

R-18^0 -8-

DISCUSSION OF TEST RESULTS

Smooth Water Performance

Referring to Figure 5, which is a summary of test results for the

P-l hull operating at a gross weight of 55,000 lbs. and an LCG 12.5 ft.

fo-ward of the transom, the following hydrodynamic characteristics are

evident.

0 Transom Flap and No Chine Flap: With zero transom flap, the hump speed

is approximately 15 knots, the trim angle is nearly 22 , and the EHP is

1050 hp. Both the trim and horsepower decrease rapidly as the speed is

reduced. For instance, at 10 knots, the trim angle is nearly zero and the

EHP is only 100 hp. As the speed is increased beyond 15 knots, there is a

rapid decrease in trim angle and only a slight decrease in EHP. At 15

knots, the craft was fully planing in the sense that the flow separated

clearly from the chines and transom.

Effect of Transom Flaps: The effectiveness of the transom flap is clearly

demonstrated in Figure 5. It is seen that, for full flap deflection of

15 , and at a speed of 15 knots, the hump trim angle is reduced to 15

and the EHP is decreased to approximately 800 hp—nearly 300 hp less than

for the 0 transom flap position. A larger flap or a flap deflection greater

than 15 is expected to further reduce the hump trim and resistance. At

speeds in excess of 15 knots, smaller flap angles are required to achieve

minimum drag at a given speed. For instance, at 25 knots a 12.5 flap

angle is required; at 35 knots a 10 flap angle is required, while at **0

knots a 7.50 flap angle is used. At these higher speeds, greater flap angles

would develop diving moments that would immerse the bow and, hence, increase

the drag. This effect is demonstrated at 35 knots where it is seen that an

increase in flap deflection from 10° to 12.5° increased the EHP by nearly

300 hp. In fact, the transom flap enables the craft to approach an optimum

trim angle of approximately *» where the lift-drag ratio is a maximum.

This first exploratory study was not intended to develop the best flap

configuration but rather to demonstrate their effectiveness. It is believed

that, based upon these data and available analytical procedures (Ref. 2),

an optimum flap can be designed for a heavily loaded planing hull.

R-18*»0

-9-

Effect of Chine Flaps: Figure 8 presents results for the P-l model with

added chine flaps for a gross weight of 55,000 lbs. and an LCG of 12.5 ft.

forward of the transom. A comparison of these results with those in

Figure 5 at optimum transom flap deflection leads to a direct evaluation

of chine flap effectiveness. It is seen that, for maximum deflection of

transom flap, the addition of the chine flaps results in a hump EHP of

680 hp compared with 810 hp for the case of no chine flaps. At 35 knots,

the addition of chine flaps reduced the EHP from 760 hp to 600 hp. In addi-

tion, the running trim angles for the entire speed range were less than

those for the P-l without chine flaps. This is a direct consequence of

the lower beam loading associated with the addition of the chine flaps.

As with the case of the transom flap study, no attempt was made

to optimize the chine flap design. However, the use of the present data

and the analytical procedures of Ref. 3 can achieve this optimization.

It does appear that the addition of chine flap is hydrodynamically

beneficial in the planing range and may present an option in the

total craft design. One other possible advantage offered by the chine

flaps is that, at pre-planing speeds, the submerged chine flaps should

increase the damping in roll, heave, and pitch tnd thus mitigate the mo-

tions while loitering in a seaway.

Effect of Increased Displacement: A comparison of the results in Figures

5 and 6 shows that, at 35 knots, an increase in displacement from 55,000 lbs.

to 60,000 lbs. (9-1%) results in approximately a S% increase in maximum EHP.

This is in direct proportion to the increase in gross weight and follows

from the fact that the transom flap angle was adjusted so that, for both

gross weights, the model ran at essentially the same trim angle. It is,

of course, well known (Ref. 3) that the lift-drag ratio of a planing hull

is primarily dependent upon the running trim angle. At hump speed, the

EHP for the 60,000 lb. gross weight is nearly 18$ larger than for the

55,000 lb. case. The running trim for the heavier gross weight was larger

than for the light weight due to the fact that the transom flap was set

at maximum deflection (15 ) for both loadings. It is believed that, with

more transom flap available at the hump condition, the hump trims for both

displacements could be made identical and, hence, the EHP would increase

in direct proportion to the increase in gross weight.

R-1840 -10-

Effeot of LCG Position: The effect of forward movement in LCG was in-

vestigated with the P-] model at a gross weight of 55,000 lbs. Table 2

presents data for an LC6 of 12.5 ft. forward of the transom while Table k

presents data for an LCG of 13.5 ft. At 15 knots and a transom flap de-

flection of 15 , the forward LCG resulted in a reduction of running trim

from 15.2 to 10.9 • Ordinarily this should reduce the EHP. However, it

is seen that the EHP actually increased. This follows from the fact that,

at the forward LCG, the bow immersion increased, thus increasing the drag.

It is believed that a transom flap angle deflection less than 15 would

have reduced the bow immersion and, thus, avoided the large drag increase.

At 35 knots and a transom fl p deflection of 7.5 , the forward LCG reduced

the trim angle from *».1° to 3.7° and increased the EHP from 750 to 837 hp.

This increase in EHP follows from the fact that 3«7° trim is less than the

optimum trim (betweenk and 5 ) where the lift-drag ratio is a maximum.

It appears then that a forward LCG can be accommodated by the use of tran-

som flap angles smaller than those used for the aft LCG position and thus

reduce bow immersion. Aft center-of-gravity positions were not investigated

in this study. However, it can be postulated that the higher trim angles

which will be associated with an aft LCG can be overcome by the use of

transom flap size and settings greater than those for the mid LCG position,

particularly at hump speed.

Maximum Lift-Drag Ratio for P-l Model: It is interesting to note from the

data given in Table 5 that, at 35 knots, the P-l model with chine flaps

and optimum transom flap setting has a lift-drag ratio of 55,000/5590 = 9.8.

This is a somewhat higher value than experienced for typical planing hulls.

It is attributed mainly to the effect of the transom flap increasing the

pressures on the aft end of the basic planing bottom and, hence, improving

its hydrodynamic efficiency.

Effect of Zero Deadrise: A comparison of the EHP for the inverted vee

bottom hull without chine flaps (Figure 5) with the EHP tor the flat bot-

tom hull without chine flaps (Figure 9) shows that, at optimum transom

flap angles, the flat bottom hull requires nearly kO hp less than the P-l

for most of the speed range. This follows from the slightly smaller trim

angle associated with the flat bottom hull. Comparing the P-l and zero

deadrise hulls with chine flaps (Figures 8 and 10) at a gross weight of

55,000 lbs. and an LCG of 12.5 ft. forward of transom shows an essentially

similar result.

-11-

Effeot of Large Transom Flap: For all configurations and loading previous-

ly discussed, the EHP at hump was always somewhat larger than the EHP at 35

knots. This was attributed to the large trim angle at hump which could not

be further reduced with the limited size of trim flap used in the study. A

brief investigation was made of the effect of a full-span transom flap at-

tached to the flat bottom hull with chine flaps. It is seen (in Figure 10)

that, for a 2.5 deflection of the large transom flap, the EHP at hump was

reduced to approximately 560 hp—just about equal to the EHP at 35 knots.

Further exploratory studies to reduce the hump trim are recommended. The

I present test results and the analytical methods of Ref. 2 and 3 provide

the guidance for flap design.

It is interesting to note from the data given in Table 7 that, at

35 knots and a transom flap setting of 5.0 , the flat bottom hull with

chine flaps has a lift-drag ratio of 10.3- This is somewhat larger than

obtained with the P-l at 35 knots.

Porpoising Tendenay: For the P-l and flat bottom hull, porpoising was ob-

served at 30 knots with the LCG at 12.5 ft. forward of the transom and with

I the transom flap set at zero degrees. A 2.5 increase in transom flap

angle completely eliminated all porpoising tendencies.

Sunrnary of Smooth Water EHP: Figure 11 presents a summary of EHP versus

speed for the four tested configurations at a gross weight of 55,000 lbs.

and an LCG of 12.5 ft. forward of the transom. This plot demonstrates

the reduction in smooth water EHP which is associated with controllable

transom flaps and chine flaps. In the extreme case, it is seen that, at

hump speed, the EHP of the P-l with 0 transom flap and no chine flap is

I 1,075 hp which, for the flat bottom hull with chine flaps and a large tran-

som flap, the EHP is reduced to 550 hp. Similar reductions in EHP are seen

at 35 knots. Although flaps do appear to offer hydrodynamic advantages,

} their incorporation in an LVA prototype is recognized to be dependent upon

; considerations of additional design aspects.

Performance in Head Sea State 2

It will be recalled that rough water studies were made only with

the P-l hull; the P-l hull with chine flaps and the flat bottom hull with

chine flaps. The loading was always 55.000 lbs. with the LCG 12.5 ft.

forward of the transom. In all cases, the transom flap was included. The

R-18A0 -12-

following discussions will be based on the data plotted in Figures 12

through 18. Statistical results are presented since motions and acceler-

ations of planing craft are non-1inearly dependent upon wave height (Ref. 1).

Significant Pitch Motions: Figure 12 demonstrates the variation of signif-

icant pitch oscillations (bow up or down) with speed about the mean pitch

given in Table 8. It will be recalled the significant pitch values

represent the average of the 1/3 highest values obtained in a test run.

In all cases, it is seen that transom flap deflection is most effective

in reducing the pitch oscillations. For example, at 25 knots, the pitch

amplitude is 6 for the P-l without chine flaps and 0 transom flap. The

pitch amplitude is reduced to 2.7 for a transom flap deflection of 12.5 •

An examination of Figure 12 shows that it is possible to limit the pitch

amplitude to approximately 2.5 for all speeds and all tested configura-

tions. This pitch value is comparable to those experienced by conventional

planing hulls.

Significant Heave Motions: Figure 13 demonstrates the variation of signif-

icant heave oscillations (up or down) with speed. Again, it is seen that,

with proper transom flap selection, the heave oscillations can be limited

to values between 0.5 ft. and 1 ft. for the entire range of test speeds

and for all configurations. The trend is for heave oscillations to decrease

with increasing transom flap deflection. This follows from the fact that

the motions and impact loads on a planing hull decrease with decreasing

hull trim angle (Ref. 1). Transom flap deflections, of course, reduce

running trim angle.

Significant Bow Accelerations: Figure 1*» shows that the significant bow

accelerations (up) increase with increasing speed. Further, the magnitude

of these accelerations decrease with increasing transom flap deflection.

Again this follows from the lower hull trim angles associated with increas-

ing transom flap deflection. As previously explained, the number of wave-

hull impacts obtained in this exploratory study is not adequate to make

a precise statistical evaluation of the effect of deadrise on impact loads.

This will ba determined in a subsequent detailed study of LVA seakeeping.

However, with the test sample collected, it can be seen that there is some

small difference between the inverted vce-bottom and the flat bottom hulls.

R-18*»0 -13-

At 35 knots, the P-l with chine flaps experienced a significant bow-up

acceleration of approximately 1.6g with 12.5 transom flap deflection.

For the same operating conditions, the flat bottom hull with chine flaps

experienced 1.3g's. The P-l without chine flaps encountered a signifi-

cant bow acceleration of 1.25g with 7-5 transom flap.

Significant Center-of'-Gravity Accelerations: Figure 15 presents plots

of the significant center-of-gravity accelerations versus speed. The var-

iations with speed, configuration, and transom flap deflection are essen-

tially similar to those described for the bow accelerations. The magni-

tude of these C.G. impact accelerations are nearly one-half those at the

bow. For instance, at 35 knots, the P-l experienced a significant C.G.

acceleration of 0.6g.

Significant Stern Accelerations: Figure 16 presents plots of the signif-

icant stern accelerations versus speed. Again, the stern accelerations

increase with speed and decrease with increasing transom flap angle. The

magnitude of these stern accelerations are nearly one-half those at the

center of gravity. For instance, at 35 knots, the P-l experienced a

significant stern acceleration of only 0.25g for a transom flap setting

of 12.5 and0.32g for a transom flap setting of 7.5 •

Comparison of LVA Accelerations with Those for Other Planing Craft: In

order to properly interpret the measured LVA accelerations, the significant

accelerations at the C.G. are compared in Figure 20 with those for other

planing hulls previously model-tested at the Davidson Laboratory. An en-

velope bounding the maximum and minimum values of LVA accelerations for

all tested configurations is shown and compared with measured values for

6 other planing craft. These planing craft are identified only as to length,

| test sea state, and speed. It is seen that the LVA accelerations are well

within the range of values for typical planing hulls. In fact, some of the

i comparison hulls experienced nearly twice the values of LVA center-of-gravity l I acceleration.

Estimate of Habitability in a Seaway: At the conclusion of the present rough I

water study, which generated data in a form which is conventional for planing

hulls (i.e., statistics of motions and loads), it appeared to be useful to

compare the measured impact accelerations with vibration exposure criteria

of MIL-STD-U72A. It will be recalled that this criteria relates curves of

R-l8*»0 -14-

1/3-octave band rms "g" versus encounter frequency to levels of proficiency.

Unfortunately, it was not convenient at that time to properly process the

accelerations signals to generate such information. However, for the pur-

poses of a "first look" at the tolerance levels, an engineering type an-

alysis was made to recast the acceleration data into 1/3-octave band g's.

The engineering type analysis is admittedly not rigorous, but never-

theless is based on sufficiently applicable assumptions so as to adequately

develop a "first evaluation" of tolerance levels. The following assumptions

have been made.

1. The variance of the acceleration spectra can be divided into

about three parts--i.e., there are only about three octave bands of signif-

icance. This is a conservative assumption since, if there are more third

octave bands, the variance of a given third octave band would be a smaller

portion of the total.

2. From (1) it then follows that the peak variance will be 1/3 the

total variance observed for accelerations. Accordingly, the magnitude of

an rms 1/3-octave band acceleration may conservatively be approximately

1//J times the total rms acceleration.

3. An examination of the LVA model acceleration data indicates

that the significant center-of-gravity accelerations quoted in this report

are approximately 2.25 times the total rms. Accordingly, the magnitude of

the 1/3-octave band accelerations may be 1/2.25 f$ = 1A times the signifi-

cant accelerations.

4. The center frequency is taken to be the number of acceleration

maxima divided by the sample time. The assumption is that the result will

be an estimate of the frequency position of the largest rms 1/3 band

octave result.

The results of this simple analysis are shown in Figure 21. This

figure is really two plots superimposed. The criteria from the MIL-STO

are indicated for 1, 2.5 and k hours exposure time. The inner vertical

scale pertains to the criteria. The outer vertical scale applies to

significant accelerations for various planing craft, including the LVA,

and are plotted against average encounter frequency. It is noted that

R-18J»0

-15-

the inner and outer scales differ by a factor of A so that, if the as-

sumptions are reasonably correct, Figure 21 represents a comparison of

acceleration levels achieved for various designs with the MIL-STD cri-

teria.

It would not be entirely proper to conclude that the best of the

LVA designs will meet the vertical vibration criteria at the center of

gravity. However, it is proper to observe, from Figure 21, that the LVA

is in the "ballpark". This was the purpose of the present simplified

study. Future analysis of LVA acceleration data will be made using standard,

consistant techniques.

Mean Effective Horsepower (EHP) in Waves: Figure 17 presents plots of

the EHP versus speed for each of the three configurations tested in sea

state 2. It is seen that the minimum test speed is 15 knots. At lower

speeds, both the smooth water and rough water EHP were very small so that

it was decided to concentrate on test speeds of 15 knots and greater.

For the most part, the smallest values of EHP were developed at

the lowest test values of transom flap. It was observed that, as the

transom flap was deflected in a seaway, the mean trim would decrease,

the bow would contact the waves more frequently, and the mean resistance

would increase. It would be well to investigate the effect of smaller

than tested flap angles (even negative) on the rough water resistance.

A summary plot comparing the lowest values of resistance for each

tested model is given in Figure 18. It is noted that, in general, the

rough water EHP is essentially constant for speeds between 15 and 25 knots

and then increases rapidly with increasing speed. The EHP for the P-l

without chine flaps is approximately 1110 hp in the 15-25 knot speed

range. It decreases to 900 hp when chine flaps are added and is just over

800 hp for the flat bottom hull with chine flaps. At 30 knots, the rough

water EHP is 1200, 980, and 9^0 for these three hulls.

Comparing these results with the smooth water resistance given in

Figure 11, the following tabulation of rough water EHP increment (expressed

as a percentage of smooth water EHP) is given:

R-18^0 -16-

vK=15 VK = 25 VK=30

38% h3% 6k%

28 58 75

33 58 77

EHP Increment in Sea State 2

Configuration

P-l

P-l with Chine Flaps

Flat Bottom with Chine Flaps

These rough water EHP increments are larger than normally experienced

with planing craft. Two features may contribute to this result. One is the

relative blunt bow form associated with the LVA hull and the other is the

small length of the craft relative to the mean wave length in a sea state

2. It is expected that "sharper" bow forms with less steep buttock lines

at the lower aft end of the bow should reduce the rough water resistance.

This should be further investigated.

Comparison of Measured and Predicted

Smooth Water EHP for 0° Transom Flap

Analytical techniques for predicting smooth water performance of

prismatic planing hulls are available (Ref. 3) but have not yet been com-

pared with experimental data for heavily loaded hulls such as characterized

by the present LVA. The data in this report offer an opportunity to make

this comparison. Calculations were made for the P-l and the flat bottom

models with zero transom flap deflection and with and without the 3~ft.

wide chine flaps. The inverted vee-bottom was assumed to have effective

prismatic deadrise of 10 . The partial span transom flap at zero degrees

was accounted for in the calculations by assuming it to be a full span

flap having a chord such that its area was equal to the area of the actual

flap. Since the full-scale flap had an area of 6.5x3" 19.5ft2, the

j "effective" flap used in the prismatic hull calculations had the follow-

ing dimensions:

j Hull Bern %featl:ve Z(feC%Z i Flap Span Flap Chord

\ II' (No Chine Flaps) U' 1.77'

17' (With 3' Chine Flaps) 17' 1.15'

R-18V« -17-

Although hydrodynamic formulations for deflected flaps are presented

in Ref. 2, they are not applied in the present study of the LVA since it

has been found that further development is required to establish equilibrium

conditions for a free-to-trim and free-to-heave flap-controlled planing

hull. It is expected that this work will be undertaken in the subsequent

phase of this development.

Figure 22 presents comparisons between calculated and measured EHP

and equilibrium trim for the following four models--all with a 6.5' span

by 3' chord transom flap at zero degree deflection (full scale).

1. P-l - No Chine Flaps

2. P-l - With Chine Flaps

3. Flat Bottom - No Chine Flaps

b. Flat bottom - With Chine Flaps

The bare hull EHP and equilibrium trim have been calculated follow-

ing the procedures of Ref. 3 and k and representing the transom flap as

previously discussed. The vertical center of gravity is taken to be 3-5 ft.

above the keel and the thrust line is parallel to and 1.25 ft. below the

keel. It is seen that the agreement between calculated and measured hump

values is within 53 for the hulls without chine flaps and within 3% for hulls with the 3' wide chine flaps. The agreement is considerably better

at higher speeds.

R-18^0 -13-

2.

3.

CONCLUSIONS

Model tests of two planing hull concepts (an inverted vee-bottom

and a flat bottom) for the LVA were conducted at a nominal, full-scale,

gross weight of 55,000 lbs. and an LCG 12.5 ft. forward of the transom.

The following conclusions are based on an analysis of the test results

which wereobtained over a range of test speeds from 10 to *»0 knots.

Smooth Water

1. The hump trim of the craft occurs at approximately 15 knots

planing speed.

The addition of transom flaps is effective in reducing the

trim and EHP at hump speed.

Proper deflection of transom flaps provide trim control to enable

the craft to plane at near optimum trim angle at speeds in excess

of the hump speed.

k. The addition of retractable chine flaps is beneficial in

reducing EHP and trim throughout the speed range.

5. Based on the present test data, procedures tor optimum tiansom

and chine flaps can be developed.

Porpoising occurs at speeds in excess of 30 knots, but is easily

eliminated by small deflections of the transom flap.

For the zero flap deflection case, the computed and measured EHP

and equilibrium trim are in good agreement.

8. The lift-drag ratio of the craft with chine and transom flaps is

approximately 10 at 35 knots.

Rough Water

Model tests in a head sea state 2 lead to the following conclusions:

Pitch and heave oscillations decrease with decreasing trim angle.

Over a speed range between 15 and 3 knots, the pitch and heave

motions are essentially independent i.f speed if, at each speed,

the craft is properly trimmed by the transom flap.

The motions of the LVA are not unlike those of convential planing

craft.

6.

7.

I.

2.

3-

R-lMO -19-

k. The impact accelerations decrease with decreasing trim angle,

but increase with increasing speed,

5. Typically, the bow accelerations are nearly twice those at the

center of gravity while the stern accelerations are nearly one-

half those at the C.G.

6. The levels of impact acceleration are not unlike those of well-

designed planing hulls.

7. Based on an elementary 1/3-octave band analysis, the rms g's at

the center of gravity are within the 1 hour tolerance level as

defined in MIL-STD-U72A.

8. The added EHP in waves is approximately 50% higher than the smooth

water EHP. This is attributed to the blunt bow form and to the

small size of the LVA relative to the waves in a state two sea.

Improvements in bow form are recommended.

3- There is only a small difference in impact accelerations between

the inverted vee bottoms and flat bottom hulls.

10. Further hull form development is recommended to reduce accelera-

tions in a seaway.

R-JMO -20-

ACKNÖWLEDGEMENT

The authors would like to acknowledge the contribution of Mr. John

K. Roper of Roper Associates to all aspects of this study and to Mr. John

Dalzell in the analysis of rough water data. The cc stant encouragement

of Mr. David Halper of Code 112 of NSRDC, who was technical coordinator,

is also acknowledged.

\

—MM^MHMlijimg^im^jgj^jjn^ gjHUj tmm

R-18^0 -21-

REFFRENCES

1. Fridsma, Gerard: "A Systematic Study of the Hough Water Perform- ance of Planing Boats, Irregular Waves - Part II" Davidson Labor- atory, Stevens Institute of Technology Report 1495, March 1971

2. Broun, P.W.: "An Experimental and Theoretical Study of Planing Surfaces with Trim Flaps" Davidson Laboratory, Stevens Institute of Technology Report 1463, April 1971

3. Savitsky, Daniel: "Hydrodynamic Design of Planing Hulls" Marine Technology SNAME, Vol. 1, No. 1, October 1964

4. Bloimt, Donald L. and Fox, David L.: "Small Craft Power Prediction" Paper presented at Western Gulf Section of SNAME, 14 February 1975

'*

R-1840

TABLE 1

LVA HULL P-l

Load 50,000 lb LCG 12-5 ft fwd of transom

Wetted Trans• Flap deg

Speed kt

Drag lb

EHP Trim deg

Heave ft

Length Area ft sq ft

0 10.04 7080 216 2.4 - .8 25-0 418

0 14-98 17230 793 20.0 1.6 17-5 231

0 20-03 14560 896 15-9 2-7 14.0 174

0 25-02 11280 867 11-5 3-2 13-5 168

0 30.05 9180 847 8.5 3-3 13.C 162

R-1840

TABLE 2

LVA HULL P-l

Load 55.000 lb LCG 12-5 ft fwd of transom

Trans- Flap deg

0

Speed kt

10.04

Drag lb

2950

EHP Trim deg

Heave ft

Wetted Length Area

ft sq ft

9» - .2 1-7 23.0 304

0 14-98 20900 962 22.0 1-9 16.5 274

0 19-97 17390 1067 17-5 3-1 14.5 179

0 25-00 13590 1044 12.4 3-5 13-5 168

0 30-05 11140 1028 9-2 3-5 13-5 168

5-0 35-06 7550 813 5-2 3-3 14.5 179

5-0 40.06 8850 1089 4.0 3-3 16.0 196

7-5 30-07 8370 773 6-3 3-2 16.0 196

7-5 35-06 6970 750 4.1 3.2 15-5 191

7-5 40.06 6630 816 2.8 31 17-0 208

10.0 35-06 6970 751 3-7 3-1 16-5 202

12-5 25-04 9970 767 7-5 3-0 17-5 213

12.5 30.05 7910 730 4.6 3.0 17-5 213

12-5 35-08 9750 1050 2-3 2.9 20.0 242

15-0 14-98 16940 779 15-2 1.4 20.5 362

15-0 20.03 12990 799 10.9 2.4 18.5 225

■"■""H"!«

R-1840

TABLE 3

LVA HULL P -1

Load 60,000 ! lb LCG 12-5 ft fwd transom

Wetted Trans- Flap rip n

Speed kt

Drag lb

EHP Trim deg

Heave ft

Length ft

Area sq ft

0 10.04 8050 248 2.4 - 1.0 25-0 443

0 14.98 23180 1067 23-0 1.9 17-2 243

0 20.03 20070 1235 18.5 3.2 14-5 179

0 25-02 15080 1159 13-5 3-9 13-0 162

0 30.07 12050 1113 9-9 3-9 13-0 162

2-5 30.05 11220 1036 8.8 3-7 13-2 165

5.0 25-04 13490 1038 11.4 3-5 18-5 225

5.0 30.05 10490 968 7-9 3-6 14.5 179

5.0 35-06 8610 927 5-6 3-5 15-0 185

5.0 40.06 7566 931 4.1 3.5

7-5 30.05 9870 911 7.0 3-4 15.1 186

7-5 40-02 7340 903 3.1 3.4 16-5 202

10.0 25-02 12370 950 9-5 3-3 15-5 191

10.0 30.07 9200 850 5-9 3-3 16-5 202

10.0 35.06 7730 832 3-7 3-3 17-5 213

12.5 20.03 16550 1018 13-5 2-7 17-0 208

12.5 25-04 11260 866 8.2 3.2 17-0 208

12.5 30.05 8450 779 4-7 3.2 17-7 216

12.5 35.06 9760 1051 2.9 3-1 20.2 244

15.0 14.98 19630 903 16.0 1.4 20.5 357

15-0 20.03 15590 959 12.3 2.6 17-0 208

jä&iii

R-1840

TABLE 4

LVA HULL P-J

Load 55,000 lb LCG 13-5 ft fwd of transom

Wetted Trans. Flap deg

Speed kt

Drag lb

EHP Trim deg

Heave ft

Length ft

Area sq ft

0 14-98 17970 827 18-7 1-8 19-5 331

0 20.03 16210 997 15-5 2-7 16-0 196

0 25-04 12480 959 11-5 3-5 14.0 174

0 30.05 10130 935 8-5 3-4 13-5 168

5.0 35-06 7680 825 4-9 3-1 16.0 196

5-0 40.02 6990 859 3-7 3-2 16-0 196

7-5 30.07 8350 771 5-9 3-1 17-0 208

7-5 35-06 7780 837 3-7 3-0 17-0 208

7-5 40.06 6940 854 2-8 3-1 17-5 213

10.0 35-06 7930 853 3-3 2-9 18-7 228

15.0 14.98 18U0 835 10.9 0.8 21.5 369

15.0 20.03 15100 929 10.4 2.0 20.5 247

■ ^..v^^,^^

R-1840

TABLE 5

LVA HULL P-l

LCG Load 55,000 lb

12-5 ft fwd of transom With Chine Flaps

Trans- Flap deg

Speed kt

Drag lb

EHP Trim deg

Heave ft

Wetted Length

ft Area

sq ft

0 14-98 18350 844 18-4 2-7 17-2 314

0 20.03 i2570 774 12.2 3-5 13-2 244

0 25-04 9240 771 8.0 3-7 12-7 235

2-5 30.07 6690 618 4-7 3-5 13-5 249

5-0 30.07 6130 586 4.1 3-4 13-7 253

5-0 35-06 5800 624 2-7 3-3 12.5 231

5-0 40.06 5650 695 1.8 3-3 13-7 253

7-5 30.07 6100 564 3-4 3-3 15-0 275

7-5 35-06 5590 602 2.0 3-2 15-7 287

7-5 40.02 5770 710 1.1 3-2 17-0 310

12.5 25-04 7170 552 4-4 3-3 17-5 318

12.5 30.07 5810 536 2.1 3-2 17-7 322

15.0 14.98 14960 689 12.8 2-3 19-0 345

15-0 20.01 9770 603 7-5 2-9 17-2 314

■an ÜÜ jaflfiaflaliaMIIIHiMln

R-1840

TABLE 6

LVA FLAT BOTTOM HULL

Load 55> 000 lb

LCG 12 •5 ft fwd of transom

Trans- Wetted Flap Speed Drag EHP Trim Heave Length Area deg kt lb deg ft ft sq ft

0 10.06 6060 187 4-4 - .1 23-5 354

0 1^-98 18160 836 21-3 1-9 17-5 280

0 20.03 16320 1004 16.8 2-7 15-5 188

0 25-02 11670 897 11.9 3-3 13-7 164

2-5 35-06 7180 773 5.4 3-1 14-7 180

2-5 40-02 6800 836 4.1 3-1 15-2 185

5-0 35-06 6735 725 4-5 3.0 16.5 199

5-0 40-06 6690 823 3-2 3-0 17-2 208

7-5 30-05 7640 705 5-6 3-0 17-5 210

7-5 35-06 6710 722 3-5 2-9 19-5 232

10.0 25.02 9940 764 7-9 2-8 17-7 213

10.0 30-07 7920 731 4-7 2-8 20-0 238

12-5 20-03 12810 788 11-2 2-3 18-5 219

12-5 25-02 S530 732 6.6 2-7 20.0 238

15-0 14-98 16250 748 13-6 1.3 20.5 345

15.0 20.03 12830 789 10.2 2-2 20.0 238

^^M^^^^^^^^^^^^^^^^^^^flMH^UHMf

R-1840

TABLE 7

LVA FLAT BOTTOM HULL

LCG Load 55,000 lb

12.5-ft fwd of transom With Chine Flaps

Trans. Flap deg

Speed kt

Drag lb

EHP Trim deg

Heave ft

Wetted Length Area

ft sq ft

0 14-98 17300 796 17.4 2-5 16.5 298

0 20.01 10680 656 10.9 3-2 15-0 273

0 25-04 7960 612 7-4 3-5 14.0 256

0 30.05 6170 569 5-0 3-4 13.5 247

2-5 30.07 6080 562 4.3 3-3 14.0 256

2-5 35-06 5450 587 3.0 3-2 14.2 260

2.5 40.06 5520 679 2.1 3-2 15-0 273

5-0 30.05 5870 541 3-7 3-3 15-0 273

5-0 35-06 5340 575 2.4 3-2 16.2 294

5.0 40.06 5790 712 1.5 3-1 17-5 3-5

7-5 30.05 5770 533 3-0 3-2 17.0 307

7-5 35-06 5760 620 1-7 3.1 18.7 337

12-5 25-02 6780 521 4.0 3.1 18.2 328

15-0 14-98 14.98

14240 13800

655 635

12.9 12.3

2.4 2.2

19-0 19-5

341 345

15-0 20.03 8850 545 6.9 2-9 17.5 315

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R-1840

FIGURE 12

SIGNIFICANT PITCH VS

SPEED

Sea State 2 Load 55,000 Lb LCG 12-5 ft FWD

O

O

o o

LVA Flat Bottom Hull Chine Flaps

Transom Flap Angle

A A 0 0 ° 2-5 A 5-0 D

X □ 7-5 x X 10.0 v

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Speed, kts

30 35 ko

R-1840

FIGURE 13 SIGNIFICANT HEAVE

VS SPEED

Load 55,000 Lb

Heave, ft Up or Down

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R

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O I LVA Hull P-l No Chine Flaps

20 25 Speed, kts

30

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R- 1840

2 Acc.g Up

FIGURE 14 • SIGNIFICANT BOW ACCELERATION

vs ■ • STEED

SEA STATE 2 ;

Load 55,000 Lb LCG 12-5 ft Fwd

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<3>

O

G

+ □ X

A □

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+

X D X

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□

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10

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15

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20

+

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V

25

Speed, kts

X □ + X

LVA Hull P-l No Chine Flaps

30 35 40

R-I 840

FIGURE 15

SIGNIFICANT CG- ACCELERATION VS

SPEED

SEA STATE 2

Load 55,000 Lb

| 1.0

[

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g

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i O

§

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A

3 X

A a

x

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10.0 12-5 15-0

A D x V

+

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©

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10

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LVA Hull P-l No Chine Flaps

20 25 30 Speed, kts

S

+

35 kO

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•5

R-18k0

FIGURE IN-

SIGNIFICANT STERN ACCELERATION

VS SPEED

SEA STATE 2

Load 55,000 Lb : LCG 12-5 ft Fwd

LVA Flat Bottom Hull Chine Flaps

§ §

&

Transom Flap Angle

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LVA ,iull P-l No Chine Flaps

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FIGURE 18

MEAN EFFECTIVE HORSEPOWER

HEAD SEA STATE 2

A = 55,000 LBS. LCG =12.5 FT. F'W'D TRANSOM

EHP

— 1400

1200

1600 hp

1000

800

600

400

200

10 Deadrise Optimum Transom Flap

10 Deadrise Transom and Chine Flaps

0 Deadrise Transom and Chine Flaps

J I I 1 10 20

Speed, Knots

30 40

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R- I 8^+0

FIGURE 19

WAVE SPECTRA Significant Height 2.2 Ft

Sea State 2

Densi ty

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Pierson-Moskowitz ! Davidson Laboratory

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R-18^0

FIGURE 22

COMPARISON OF COMPUTED AND MEASURED RESULTS

EHP EHPCTes*) 0 TRANSOM FLAP Trim

No Chine Flaps

10 20 30 Speed, Knots

Trim i EHP lOOOhp

800

25°

:HP

«

\

600

— i*00

\Tr im \ \ \

15-

20 —

200 5- P-l

With Chine Flaps

j ; L 10 20 30

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— 800

t EHP

20 —

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\

\ \

10__

— 200

f 3 = 0°

^A5-

1 With Chine

I Fl, ap s

1 10 20 30

Speed, Knots

R-I 840

APPENDIX A

Movie Sequence

Reel 1

LVA P-l Hull No Chine Flaps

Speed Transom Sea Flap State Angle

kts deg

15 15 0

15 15 2

20 15 2

25 12-5 0

25 12-5 2

30 7-5 0

30 7-5 2

35 7-5 0

35 7-5

Reel 2

2

LVA P-l Hull W th Chine Flaps

15 15 0

20 15 0

25 12-5 0

25 12-5 2

30 7-5 0

30 7-5 2

35 5-0 0

35 5.0 2

.■■■■■mill.«——

R-1840

APPENDIX A (cont'd)

Reel 3

LVA Flat Bottom Hull With Chine Flaps

Speed

kts

Transom Flap Angle

deg

Sea State

15 15 0

15 15 2

20 15 0

20 15 2

25 12-5 0

25 12-5 2

30 5-0 0

30 5-0 2

35 5-0 0

35 5.0

Large Transom Flap

2

15 2-5 0

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40

R-1840 j

APPENDIX D i ' l

LVA HULL i

Irregular Seas Test Matrix

Load: 55,000 lbs LCG: 12-5 ft

Transom Flap Angle, Peg-

Speed 0 2-5 5 0 7-5 10 12.5 15

15 X

LVA P-l W thout Chine Flaps

X

20 X X

25 X X X

30 X X X

35 > X X

40

LVA P-l With Chine Flaps

15 X

20 X

25 X x

30 X X X

35 X X

40 X X

LVA FLAT BOTTOM HULL WITH CHINE FLAPS

15 X X

20 X X

25 X

30 X X X

35 X X X

^^^gWW^—iMB^Bll^B^MgM A

DL R-75-I85O

DISTRIBUTION LIST

Contract NOOOU-75-C-07W

Project NR062-510-/I-09-75 C*38)

Mr. David h...<: „r Code 112 NSRDC (10 copies)

Mr. L. Benen Code 03221 Nav Sea (1 copy)

Mr. Joseph Fisher ONR, Code 220 (1 copy)

Mr. Ralph Cooper ONR, Code ^38 (3 copies)

Col. Bulger ONR, Code 100M (1 copy)

ONR, Code 102IP (6 copies)

Director, ONR k'iS Summer Street Boston, Mass. 02210 (1 copy)

Defense Documentation Center Bldg. 5, Cameron Station Alexandria, Va. 2231^ (12 copies)

NRL Code 2627 Naval Research Laboratory (N00173) Washington, D.C. 20375 (1 copy)

«MM» ■JHS! !PP«